The aim of the study reported here was to determine locations of dental erosion and whether or not it is possible to decide the cause of erosion from the location. One hundred and six patients with dental erosion, 54 men and 52 women, mean age of 33.6 years, were studied. Erosion was classified as one of three grades on buccal, lingual or occlusal/incisal surfaces. Dietary and gastric causes of erosion were identified by means of a questionnaire. Erosion was observed on all teeth, but was commonest on the upper incisors, canines and pre-molars, and severest on palatal surfaces. In both groups, in which erosion had gastric and dietary causes, there were cases of buccal, lingual and occlusal erosion, but the risk of lingual erosion was 1.9 times greater in the group in which erosion had a gastric cause than in the group in which erosion had a dietary cause. Our findings indicate, however, that the cause of dental erosion cannot reliably be identified by location of the lesion.